New to solar

System · September 2007

I'm installing a net-metered solar system for our residence. I know experience brings wisdom - I'm hoping to short circuit mistakes made by being a newbie and would like feedback/warnings about equipment choices I am leaning towards.
I am planning on the following:

2 AZ 225 WattSun Trackers (2 axis)
12 Evergreen 180-SL panels per tracker
SunnyBoy SB 5000US inverter
SunnyBoy WebBox - Reporting required for PBI rebate program
AC Disconnect DU221RB 30A 240VAC
DC Disconnect HU361RB 30A 600VDC

I won't be storing power - will be relying on the grid.

I will be routing the wires from the first set of panels to the second tracker location. I plan on using Midnite Solar's mnpv6 combiner to combine the outputs from the two trackers, and outputing to the house. The total run from the combiner will be around 100 foot if I use the attic space to "cut across" to the garage. It would be an additional 30 foot if I route around the house. My thought is to locate the inverter in the garage on the east wall (a bit cooler).
I'm not sure what I need to do to connect to the utility. I have a 200 amp General Electric subpanel in the garage and was going to add a 20 amp breaker to make the connection. I don't know if I need a specialized breaker to do this, or if a standard THQL breaker will do the job.

I was on the fence with the inverter and monitoring - had thought about Fronius 5100 inverter, and Fat Spaniel - so not fixed on the hardware.
I had liked the Sanyo panels, especially with the availability of light from the back with a tracker installation - can't see the $$ diference is worth it, but maybe it is.

Any thoughts/cautions would be appreciated.

Michael

mike95490 · September 2007

Re: New to solar

Michael_C wrote: »

.... going to add a 20 amp breaker to make the connection. I don't know if I need a specialized breaker to do this, or if a standard THQL breaker will do the job.

I was on the fence with the inverter and monitoring - had thought about Fronius 5100 inverter, and Fat Spaniel - so not fixed on the hardware.
I had liked the Sanyo panels, especially with the availability of light from the back with a tracker installation - can't see the $$ diference is worth it, but maybe it is.

Any thoughts/cautions would be appreciated.

Michael

AC breakers, you need what the inverter specifies, 2 breakers, 1 for each leg, grid tie outputs at 240V. You need 2 spaces in your breaker panel, for the 2 new breakers.
AC disconnect is so a lineman can be sure inverter is disconnected.

I am familiar with the monitor sw for the Xantrax GT series of inverters, and like it.
(see my web link for that) I've had no inverter troubles in just over a year & 7.1MW.

Will you be wireing trackers in parallel or series ?
What would the voltage from each tracker be ?
Underground wires ?
Have you weighed the expense of trackers, and their maintenance, vs more PV's and fixed install?
Cooling provisions for inverter? (I use a $12 grocery store clip fan & timer in my garage)
Considered 2 medium inverters (one for each array) vs 1 huge inverter (no redundancy)

BB. · September 2007

Re: New to solar

Here is a short thread with some good information for solar connection requirements and help for building inspectors to understand the requirements:

New to the Solar thing thread...

I too would suggest that you look at fixed mount solar arrays. Or, if you have the inclination, building/installing racks were you can adjust for summer/winter sun angles. I have visited a major northern California solar store (before I installed one on my home) with multiple on-site installations (including one, very large, fixed panel system). Every tracking system installed (2-4 of them?), was pointing off to the side instead of tracking the sun (one or two even had the tracker drives hanging in pieces).

You can use the Solar Radiation data set to estimate how much power you would gain with tracking vs 1 axis, or fixed mounts.

A bigger issue for you may be if you are going for the California Solar rebates (somewhere around $2.60 per watt right now?)... They have made the process much more complicated than before (last year) and it may be near impossible for a person to install a grid tied system themselves. Plus, the rebates have been delayed by months because of the new requirements (used to be based on raw system ratings--now is based on a documented site survey and may need actual production numbers to validate).

Lastly, check which type of rate plan you can get for your home... If you are still eligible for the PG&E E-7 Time of Use Rate, and the panels will supply a significant amount of your weekday noon-6pm power, go for it. Otherwise, unless somebody can prove you will save money with the other TOU rate (I think it is E-6), I would try and go with the plain old E-1 residential plan (California, earlier this year, forced people into the E-6 TOU rate plan and for smaller solar installs--they actually saw an increase in their solar bills). The E-6 may save you some money--but it is so complex (and higher rates go well into the night after the sun has set), that only the most committed solar fan would be able to insure that everyone at home is using appliances at the appropriate times.

You are working with the local building inspector(s) and PG&E to approve your Grid Tie installation? Hopefully, this is not your first time, or you have a local solar installer doing this work for you.

Installed my Grid Tie inverter inside my garage since it is usually cooler than outside (in the summer)--although it does not get any breezes. If your inverter will get sun--probably would be helpful to install a shade/plant a tree to keep it cooler.

Lastly, the Sanyo modules (if they are the ones I am thinking of) are something you should probably stay away from. The chemistry has a bad reputation for failing output (early life failures) with other vendors. See this thread from 2005 on another solar forum (Solar Guppy may have updates on the Sanyo panels in 2007).

-Bill

System2 · September 2007

Re: New to solar

mike90045 wrote: »

AC breakers, you need what the inverter specifies, 2 breakers, 1 for each leg, grid tie outputs at 240V. You need 2 spaces in your breaker panel, for the 2 new breakers.

Thanks for your response.
I should have said double pole breaker - I don't know if there is a special "back-fed" breaker - I've seen a requirement that the breaker be secured so it can't be easily pulled out. Don't know if there are any other requirements that require a special type of breaker.

AC disconnect is so a lineman can be sure inverter is disconnected.

The inverter has integral disconnect and circuitry which satisfies the utilities requirement for decoupling when the grid goes down - my county requires a separate A/C and D/C disconnect to allow servicing the inverter.

I am familiar with the monitor sw for the Xantrax GT series of inverters, and like it.
(see my web link for that) I've had no inverter troubles in just over a year & 7.1MW.

The Xantrax software would do as much as I would need/want. The main reason for the monitoring system (e.g, Fat Spaniel) is to satisfy the rebate rules (if going PBI route). The biggest part of the program is the remote reporting has to be done by a third party like Fat Spaniel. There may be others that are cheaper, but, I have found the full list.

Will you be wireing trackers in parallel or series ? What would the voltage from each tracker be ?

I'm assuming you're talking about wiring the panel outputs - I was going to do two strings of 12 each. the Voc would be 391.2, and 310.8 under load.

Underground wires ?

I will go underground between trackers, and from tracker to house. I would go in metal conduit (emt most likely) the rest of the way.

Have you weighed the expense of trackers, and their maintenance, vs more PV's and fixed install?

I have - I don't want to put panels on the roof, so would be doing a free standing structure. So the additional cost to go to tracking is offset by the cost of the structure. I analyzed the PVWatt hourly data for tracking vs fixed - there is a 39% improvement in raw power when going to tracking. When I factored in the higher payback for excess power generated during peak demand there was a 24% improvement of tracking over fixed. The end result of the analysis was an overall reduced cost. The biggest question is reliability of the WattSun Trackers. But the worst case is I turn them into a fixed system if they fail outside the warrantee period. If it did fail, and not worth fixing, I would lose part of the 24% power production, but not everything. One thing I was hoping for was feedback on reliability of things like WattSun trackers.

Cooling provisions for inverter? (I use a $12 grocery store clip fan & timer in my garage)
Considered 2 medium inverters (one for each array) vs 1 huge inverter (no redundancy)

I hadn't thought of that - may be worth running the numbers and looking at space.

Michael

System2 · September 2007

Re: New to solar

Bill,
Thank you for your response. Especially the caution of poor tracking. Is the store you referred to close to San Jose? I'd like to visit them if they aren't too far away.

The PBI rebate program is based on actual performance, and would be 60% higher than the traditional if the tracker works as advertised. One thing you mentioned was higher rates at night for E-6 customers. We were going to the E-7 rate schedule. We're looking at around 20% use during noon and 6 pm.

We're dealing with the county, and I've talked with them on the phone, and in person. The first conversation didn't go well, but they were more than helpful when I went in and talked with them in person. Your caution is heard though. I will call PG& E and make sure a dialog is started, and ensure the path looks good (before ordering materials).

The part of the garage where I'd put the inverter has no sun - have you found any issues with your inverter? Any heat buildup/collection in area where it is located?

I've heard good things about the Sanyo, but it may all be based on the specs - they read well. The warning makes it easier to feel ok about going with the Evergreen's. Now that I say that - anyone have experience with the Evergreen's?
How about the SunnyBoy inverter?
Thanks again,
Michael

mike95490 · September 2007

Re: New to solar

If your roof mount is not an option, do you want a shaded patio ? (fixed mount site)

I too have seen several "dead trackers" 5 years old. folks just can't seem to keep them going. Even Real Goods store in Hopland, CA has some bad every time I've been there.

Figure a security plan, so you don't find empty racks some day. (pin-in-center Allen head screws ?)

What's your micro-climate like ? AM fog? PM fog? Noontime thunderstorms ?

Pick a time to sacrifice output (AM?) and a time to maximize (PM) your production, and orient thusly - maybe SouthWest, and build your patio cover/fixed rack that way, if it works best with your utility billing plan.

Put your fridges on a HD timer, and only let them run briefly in the afternoon, so you can sell at peak rate. you might even get away with a zero bill, and only half the array you have planned. (depends on the rate plan hours)

System2 · September 2007

Re: New to solar

BB. wrote: »

Or, if you have the inclination, building/installing racks were you can adjust for summer/winter sun angles.

Bill,
I forgot to mention - my original plan was to make a fixed, but adjustable, structure, and reset the tilt a couple times a year. I was going to make the azimuth adjustable in case the incentives changed for production during peak power - The suggestion in our area is to set the azimuth to optimize peak production and let total power suffer. Not a bad trade off with the high cost of producing the extra power, as long as incentives pass on to the customer. Making the azimuth adjustable would add flexibility if the rules change. Plus I figured my material cost would be under $200 extra making it adjustable. Anyway, I had planned on a fairly beef gimbaled structure that could rotate on a central post - somewhere around three thousand in material costs for two structures. Going to the full tracking, without any additional design and fab work on my part seemed like a reasonable step. It will pay for itself if it works properly during the first five year rebate period.

Michael

System2 · September 2007

Re: New to solar

Summertime fog happens, but it usually burns off by 10am. If may occur 1/4 of the days in the summertime. Very rarely do we see a thunderstorm. Maybe a half dozen times during the 30 years I've lived here.

My original thought was to do as you say - Analyzing the PVWatt hourly data, showed somewhere around 220 degrees got the best return when - factoring in the peak demand incentives. So, I was going to aim it at 220 degrees, and adjust the tilt a couple times a year.

Anyone know if the WattSun trackers fall into the same grouping of "tracking dead" after 5 years? Anybody know if the problems tend to be with the drive mechanism, or with the detection side?

Michael

BB. · September 2007

Re: New to solar

Same store as Mike, Real Goods store in Hopland, CA (Solar Living Institute)... Took my wife and family there about two+ years ago to just walk around and look at their exhibits. Probably a bit "Greener" organization than my own politics (not going to install waterless urinals and built a yurt in a major city)--but still fun to go visit.

Got my wife behind remodeling our home for efficiency (ripped the sheet-rock down to insulate, changed to double pane windows, put in operating skylights for lighting and cross ventilation, Energy Star Appliances, etc.) and eventually adding solar PV grid tie system (saw it installed and, mostly, working).

Wasn't that informational--but it was a nice trip (I did not sign up for any of the courses, and I tended to leave the sales people alone).

The "trackers" I saw, appeared to have failed because the drive mechanism failed (geared linear actuators--if I recall correctly, long ago un-repaired from the rust and caked grease). Not because hat the electronics lost track of the sun on the day I was there.

My 3kW of panels + Xantrex GT inverter is just installed on an interior two car garage wall (couple feet down from the celling) next to the kitchen door--turned out to be a good place because I can write down the daily production numbers. My garage is insulated and protected by trees--so it does not get too hot during the day and I can hold my hand on the heat sink without burning myself and have not found a need for fans (yet).

I have "typed" with on other person who has a ~2.8 kW installation (3-4 years old?) and a SunnyBoy inverter--and no problems at all (last I heard). He has a web site EVNut where you can read about his installation and his passion for electric cars.

Regarding Evergreen, their panels may need bypass diodes to be jumpered in for a Grid Tie string (may depend on model)...

Also, with any company, check their "business numbers" and see that they will be around for the next 20 years to honor their panel warranties (who knows--).

Another good place to ask questions (besides here--where Wind Sun stands behind the products they sell) about inverters and panels is Solar Guppy (inverter design engineer--he also posts here).

-Bill

System2 · September 2007

Re: New to solar

Thank you for the information on the trackers - From what I understand, most of the trackers are an offshoot of the old satellite dishes - using linear actuators. WattSun has gone with a worm gear arrangement on the azimuth adjustment - so, I can't draw any conclusions - just because they're different doesn't mean they don't have problems.
Do you find you hear any vibrations from the inverter when you're inside? I had heard this can be an issue - I had thought of putting the inverter on the wall right next to the subpanel, but decided against it after reading of the potential noise issue.
Thanks for pointing me to Solar-guppy forum. I just looked on the forum, and there were a couple postings regarding the WattSun trackers. Both have very favorable experiences - the one had a problem, after 3 years, with the "eye" which was repaired and was back up and running. For what it's worth, the other said it was built like a tank.

Thanks again,

Michael

mike95490 · September 2007

Re: New to solar

Michael_C wrote: »

I was on the fence with the inverter and monitoring

Are you permitted to monitor your own output, or are you required to have an outside source monitor you ?

Do you find you hear any vibrations from the inverter when you're inside? I had heard this can be an issue

No sound that I've noticed, and no interference to an X-10 home automation system that uses 120KHZ via power lines to communicate. Xantrex GT series is reported to FCC accepted, and likely quieter than other brands that are not.

What is X-10 ? : http://www.laureanno.com/x10-2.html

System2 · September 2007

Re: New to solar

mike90045 wrote: »

Are you permitted to monitor your own output, or are you required to have an outside source monitor you ?

Has to be a third party - indepedent
Michael

Solar Guppy · September 2007

Re: New to solar

Michael_C wrote: »

Has to be a third party - indepedent
Michael

That will cost more than the value of the electricity you generate ... dumb, very dumb

What state make that a requirement?

BB. · September 2007

Re: New to solar

California is requiring the performance monitoring...

For anyone interested, here is California's rebate (and estimated yearly production) calculator.

Here is a link to the current California "Go Solar" documents.

In the 99 page California Solar Initiatives booklet (PDF link) is the requirements for the metering system. For small systems, it is 5% accuracy (<10kW--not used for rebates as everything is paid up front), for larger systems it is 2% accuracy and has to be a separate data logger (15 minute intervals, up to 60 day storage and, it appears, needs telephone line or Internet for once per day callback / reporting). Basic costs over 5 years be less than 0.5%/1% of installed project costs, 20kW to 10kW / 10kW or less.

I guess that this is $300 on a 3kW (~$30,000 retail) install for 5 years of service (2 years may only be required on <10kW systems that don't have monthly rebate checks).

Boy--They sure have turned this rebate process into a bureaucratic nightmare of a rebate system... But what is new about that when the government gets involved in handing out "free money" to people.

-Bill

PS. Just a point of reference--PG&E charged me $277 for a new meter (roughly 1/2 for installation labor + 1/2 for actual purchase of an E-7 TOU meter). I don't think they sell the TOU meters anymore--they add $4-$5 per month to your bill for a meter leasing fee.

PPS: I was just thinking about all of the "requirements" to collect the rebates--and it adds up... 1% application fee, 1% monitoring equipment, ~$300 for TOU meter change (TOU may be optional for small systems now--not sure of that); For a 3kW system, that added up to ~$900 in equipment/charges that don't affect 1 watt of system output. $900/$6,000 rebate = 15% of rebate for a 3kW system is yanked back by regulations... Pretty neat gig.

BB. · September 2007

Re: New to solar

I guess I should add one additional warning about where to install your Grid Tied inverter... My Xantrex GT 3.0 inverter generates a fair amount of AM radio noise. A car radio within about 20' of it will pick up a whine while the sun is up (I will have to check again when the sun is down to see that the whine does disappear then). However, I do have an intercom+AM/FM (cheap) radio mounted 3' away and it is not bothered too much by the Inverter.

You may not want to install the inverter (or wiring) right behind you home audio system if you listen to AM radio a lot.

Your mileage may vary.

-Bill

mike95490 · September 2007

Re: New to solar

Solar Guppy wrote: »

What state make that a requirement?

Kalifornia, courtesy of the Governator's Solar Mandate, Jan 2007

Solar Guppy · September 2007

Re: New to solar

So for under 10kWhr inverters, the built-in Xantrex GT internal watt counter should be fine as its CEC approved, I don't get why the OP thinks he needs FatSpaniel type logging, did I misunderstand BB posts?

BB. · September 2007

Re: New to solar

You have to read the regulations/fact sheets... It appears that a logger connected to an internal inverter circuit--that is approved to within +/-5% accuracy is OK (and the system is less than 10kW CEC rating). For systems over 10kW rating, it must be an external unit unrelated to the solar inverter.

Even though a 10kW system does not get paid based on the logger data, and it need not be installed if it costs more than 1% the overall system costs--it still appears that it needs to be able 1/4 hour data and logs at least once per day (although--it is less than clear based on my quick read through).

If you use the internal inverter data logging capability, it still needs to be interfaced to a phone line or Internet connection--And I would guess that Internet interface still needs to be approved and connected through an independent organization.

-Bill

System2 · September 2007

Re: New to solar

BB. wrote: »

You have to read the regulations/fact sheets... It appears that a logger connected to an internal inverter circuit--that is approved to within +/-5% accuracy is OK (and the system is less than 10kW CEC rating). For systems over 10kW rating, it must be an external unit unrelated to the solar inverter.

Even though a 10kW system does not get paid based on the logger data, and it need not be installed if it costs more than 1% the overall system costs--it still appears that it needs to be able 1/4 hour data and logs at least once per day (although--it is less than clear based on my quick read through).

If you use the internal inverter data logging capability, it still needs to be interfaced to a phone line or Internet connection--And I would guess that Internet interface still needs to be approved and connected through an independent organization.

-Bill

There are two rebate approaches in California. One is EPBB, Expected Performance Based Buydown. This is an upfront payment based on expected production from the system. The second is PBI, Performance Based Incentives. This one is based on the amount of power generated in the first five years. Normally PBI is chosen for large installations. The only reason I am considering it is EPBB doesn't "credit" any benefit for the WattSun trackers we will be using. When I evaluated PVWatt's numbers, PBI would provide an additional $6K-$8K in rebate payments - less the cost of the monitoring/service. From what I can see, there are two aspects about reporting. There is the accuracy of the reporting from the equipment, as mentioned in other postings, plus the requirement that the report must come from an independent source. For some reason, they think I might have an interest in over-reporting the numbers - hmmm :roll:

Solar Guppy · September 2007

Re: New to solar

OK, So for all the home-owner Joes, nothing has changed and the CEC approved inverters don't need anything new, thats what I thought.

Your trying to play with the big boys and then the expensive monitoring costs come into play. You have the costs of the monitoring service, the dedicated reporting path (phone internet) , make sure you figure this all up before going down this road. Also make sure this won't put you into some different rate structure ( performace rebate ) as the under 10kWr system I have heard gets the most advantage on the TOU meters

Almost without fail, it better to have more solar panels than use a tracker. The trackers are expensive, not just the rack, but the concrete, permits ect. Then add the monintoring and compare to this total cost to just added more panels which is simple and Always makes more power.

New to solar

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